This invention relates to particular fats and fat blends, and methods for their manufacture or genetic selection/engineering, and use in foods. Consumption of such fats in appropriate amounts stabilizes or lowers the low density lipoprotein cholesterol (LDL or LDL-C) concentration and increases the high density lipoprotein cholesterol (HDL or HDL-C) concentration in human serum. This invention also relates to filled dairy products and to a method for preventing the development of off-flavors in these products.
The description and references herein are provided solely to assist the understanding of the reader. None of the information or references are admitted to be prior art to the present invention.
Coronary heart disease (CHD) is the major cause of death in the USA and other affluent nations. Plasma cholesterol, more specifically the LDL/HDL ratio, is highly correlated with risk of CHD as documented by Willett and Sacks, 324 N. Eng. J. Med. 121, 1991. The accumulation of LDL in the arterial intima is thought to lead to its oxidation, which in turn results in cascading events that induce arterial occlusion and thrombosis. High concentrations of HDL appear to block LDL oxidation and reduce the atherogenic potential of LDL. Thus, dietary means which decrease the LDL/HDL ratio (or increase the HDL/LDL ratio), especially means which would increase HDL, are desirable. Perlman and Hayes, U.S. Pat. No. 5,382,442 describe modified fat compositions and methods for decreasing total serum cholesterol while simultaneously decreasing the LDL/HDL serum cholesterol ratio. This ratio decreased as both the LDL and HDL concentrations decreased. The net LDL/HDL ratio in the serum decreased only because the LDL cholesterol concentration decreased by a greater factor than serum HDL with the dietary use of a fat-oil blend which included one to ten parts by weight cholesterol-reduced animal fat containing myristic acid, and one part by weight vegetable oil containing linoleic acid.
Within the past three years several authors have collected and analyzed a large number of independent metabolic studies relating to the effect of saturated, monounsaturated, and polyunsaturated fatty acids in the diet on serum LDL and HDL cholesterol levels. These studies have included the techniques of multiple regression analysis to examine LDL and HDL levels versus dietary intake of each group of fatty acids as separate variables expressed as the percentage of dietary energy, i.e., the total daily calorie intake of individuals in the studies.
Mensink and Katan (12 Arteriosclerosis and Thrombosis 911, 1992) made the following conclusions; xe2x80x9cReplacement of saturated by unsaturated fatty acids raised the HDL to LDL cholesterol ratio, whereas replacement by carbohydrates had no effect. Thus, under isocaloric metabolic-ward conditions the most favorable lipoprotein risk profile for coronary heart disease was achieved if saturated fatty acids were replaced with unsaturated fatty acids, with no decrease in total fat intake.xe2x80x9d Hegsted et al. (57 Am. J. Clin. Nutr. 875, 1993), combined data from 155 human trials in which LDL and HDL cholesterol measurements were available. With regard to fatty acids and cholesterol in the diet, the authors state in their published abstract, xe2x80x9c1) saturated fatty acids increase and are the primary determinants of serum cholesterol, 2) polyunsaturated fatty acids actively lower serum cholesterol, 3) monounsaturated fatty acids have no independent effect on serum cholesterol and 4) dietary cholesterol increases serum cholesterol and must be considered when the effects of fatty acids are evaluated. More limited data on low density lipoprotein cholesterol (LDL-C) show that changes in LDL-C roughly parallel the changes in serum cholesterol but that changes in high density lipoprotein cholesterol cannot be satisfactorily predicted from available data.xe2x80x9d Within this cited article, Hegsted et al. show that LDL levels increase an average of 1.74 mg/dl for each 1% increase in dietary energy represented by saturated fatty acids, while LDL levels decrease an average of 0.77 mg/dl for the corresponding amount of polyunsaturated fatty acids. Referring to the possibility of predicting changes in HDL levels in the serum, these same authors state, xe2x80x9cIt does not appear possible to develop an equation that predicts changes in HDL-C satisfactorilyxe2x80x9d and, xe2x80x9cThe errors in the regression coefficients are large; hence, little reliance should be placed on the equation.xe2x80x9d These authors calculate a very modest increase in HDL-C correlating with a dietary increase in either saturated or polyunsaturated fatty acids (0.43 mg/dl for a 1 increase in dietary energy represented by saturated fatty acids and 0.22 mg/dl for the corresponding amount of polyunsaturated fatty acids). This indicates that one would expect that for saturated fatty acids, the much smaller increase in HDL (0.43) versus LDL (1.74) per dietary energy, would typically result in a decrease in the HDL/LDL ratio as the saturated fatty acids are increased. On the other hand, the Hegsted et al. and the Mensink and Katan calculations would predict that an increase in the proportion of dietary polyunsaturated fatty acids at the expense of saturated fatty acids would increase the HDL/LDL ratio because this dietary increase caused a large decrease in LDL (approximately 2 mg/dl) and only a small proportional decrease in HDL (approximately 0.2 mg/dl). By comparison, the overall HDL/LDL serum ratios in these studies ranged from approximately 0.25 to 0.50.
Fat blends which include saturated vegetable fats in combination with polyunsaturated vegetable oils have been noted for dietary and/or cooking use. For example, Choi et al., 24(1) Lipids 45, 1989, describe cholesterol synthesis in rats with the feeding of safflower oil or linseed oil blended with palm olein in purified diets containing 10% fat. Suzuki et al.(Jpn. Kokai Tokkyo Koho JP 01, 262, 753 greater than 89, 262, 753! Oct. 19, 1989), describe the use of 40-90% natural palm oil and 60-5% natural vegetable oil in deep frying. Lim et al., (39(12) Yukagaku 1045, 1990) describe the increased oxidative stability of soybean oil blended with crude or refined palm oil or refined palm kernel oil. Murakami et al., (41 (3) Yukagahu 196, 1992) describe the feeding of soybean oil blended with an equal weight of palm stearin in diets containing 20% fat in which cholesterol metabolism was monitored in rats. Kajimoto et al., (44(6) Nippon Eiyo, Shokuryo Gakkaishi 499, 1991) describe the blending of soybean oil or rapeseed oil with palm oil, and the blending of soybean oil, rapeseed oil and palm oil to enhance the oxidative stabilities of the polyunsaturated oils. Han et al., (23 (4) Han""guk Sikp""um Kwahakhoechi 465, 1991) describe the stabilization of soybean oil against thermal and oxidative degradation by blending with an equal or greater proportion of palm oil.
The public awareness of an increased risk of cardiovascular disease associated with dietary consumption of substantial amounts of fats rich in saturated fatty acids and cholesterol has led to an overall reduction in fat intake and an increased demand for foods containing unsaturated rather than saturated fatty acids. A multiplicity of clinical studies have shown that when certain dietary levels of saturated fats are replaced by unsaturated fats, one""s total serum cholesterol level decreases. Since the milkfat, i.e., butter in dairy products contains approximately 0.22%-0.25% by weight cholesterol, more than 60% saturated fatty acids, and only approximately 4% polyunsaturated fatty acids, health-conscious individuals often prefer to consume dairy products in which the milkfat content has been reduced, eliminated, or replaced with vegetable oil.
Liquid milks are divided into various product categories based upon their weight percentage fat contents. Regular whole milk contains approximately 3.25% milkfat. Based upon an 8 fluid ounce (244 g) serving size, this corresponds to 7.9-8 grams (abbreviated g) milkfat and 35 milligrams (abbreviated mg) cholesterol per serving A xe2x80x9creduced fatxe2x80x9d product must contain no more than 75% of the fat present in the original product, while a xe2x80x9clow fatxe2x80x9d product must contain no more than 3 g fat per serving. Thus, for milk having a 244 g serving size, a 2% milkfat-containing milk is termed a reduced fat product, while a 1% milkfat-containing milk is termed a low fat milk. On the other hand, to meet the current definition of xe2x80x9cskimxe2x80x9d, xe2x80x9cnon-fatxe2x80x9d, or xe2x80x9cfat-freexe2x80x9d milk (having a 245 g serving size), the milk must contain less than 0.2% by weight milkfat, i.e., less than 0.5 g per serving, and less than 5 mg cholesterol per serving.
Filled milk is defined as skim milk which has been enriched in fat content by addition of vegetable oil. The literature on filled dairy products includes both liquid products and dried products which are reconstituted by addition of water. A number of patents describe the substitution of vegetable oils for milkfat in filled milks, to obtain nutritionally improved products which are lower in saturated fat and cholesterol. However, these modified dairy products often have an altered or unnatural flavor and mouthfeel. Howard, U.S. Pat. No. 2,659,676, describes a dried milk product prepared from skim milk and palm fat. The vegetable fat and lecithin are added to heated skim milk, which is then pasteurized, homogenized and spray-dried. Stein et al., German Offenlegungsschrift 2,444,213, describes a dried milk containing a reduced proportion of saturated fat in which polyunsaturated fat is mixed with evaporated concentrated milk which is then homogenized and dried. Kneeland, U.S. Pat. No. 3,011,893, describes a reconstituted milk prepared from powdered skim milk, vegetable oil, and water, in which a mixture of the skim milk and water is heated, vegetable oil is added, and the mixture is homogenized and pasteurized. Bundus, U.S. Pat. No. 3,488,198, describes a filled milk prepared from skim milk solids, water, fat, and a water-in-oil emulsifier. The fat may be any one of a variety of vegetable fats and oils or hydrogenated vegetable oils including coconut oil, palm oil, cottonseed, corn, soybean, peanut, olive oil, and hydrogenated derivatives of several of these oils. Arndt, U.S. Pat. No. 3,843,828, describes a simulated milk product which includes vegetable protein, whey and hydrogenated vegetable oil. Bookwalter et al., U.S. Pat. No. 4,842,884, describes a milk concentrate prepared from nonfat dry milk and vegetable oil.
Vegetable oils are also used as vehicles for adding vitamins and minerals to fortify dairy products. For example, Karinen, U.S. Pat. No. 4,803,087, describes vitamin A and D fortification of milk using an aqueous emulsion of vegetable oil and an emulsifier.
In recent years, several patents have described the composition and preparation of improved flavor vegetable oil-containing filled milks which are asserted to possess the flavor and mouthfeel of whole milk. It is suggested that these filled milks are healthier than ordinary milk due to the absence of cholesterol and the significantly lower saturated fat content. For example, Arcadipane, U.S. Pat. No. 5,393,551, describes a filled milk having a butterfat substitute providing the taste and mouthfeel of an unmodified milk with the same amount of butterfat (ranging from 1% to 4%). The butterfat substitute includes 66%-98% of a partially hydrogenated soybean oil whose major fatty acids are present in approximately the following proportions: saturated fatty acids: palmitic 11%, stearic 14%; monounsaturated fatty acid: oleic 68%. A small proportion of the polyunsaturated fatty acids, linoleic 6%, and linolenic 0.1%, are also present. Arcadipane states that a filled milk assembled from skim milk, mono- and diglyceride emulsifiers, and the above partially hydrogenated soybean oil has an extended shelf life compared to ordinary milk, and may be stored under the same conditions as ordinary milk. While the pre-hydrogenated soybean oil contains approximately 63% polyunsaturated fat, this level is reduced to only 2% to 8% after hydrogenation. Strong et al., U.S. Pat. No. 5,580,600, describes a filled milk containing principally monounsaturated vegetable oil. A high oleic acid-containing vegetable oil such as rapeseed or sunflower oil containing at least 70% oleic acid, and no more than 12% by weight polyunsaturated linoleic acid and no more than 0.5% linolenic acid is combined with skim milk, an emulsifier, a polysaccharide modifier, and a carbohydrate gel stabilizer for the emulsion. Strong et al. states that a high proportion of oleic acid-rich vegetable oil is used to avoid the problems of rancidity and off-flavors which develop after relatively short periods of storage when a substantial proportion of the added vegetable oil is in the form of polyunsaturated fats and oils. Despite the rancidity problem associated with polyunsaturated vegetable oils, Kahn et al., U.S. Pat. No. 5,063,074, describes a low cholesterol, low fat, filled milk containing polyunsaturated vegetable oil, stated to have the taste and mouthfeel of whole or 2% milkfat-containing milk. The milk contains skim milk and 1%-5% of a premix (milkfat substitute) which includes 50%-70% non-tropical (polyunsaturated) vegetable oil such as soybean oil, 6%-10% of a non-lauric emulsifier, and a substantial proportion of flavoring agent (6%-10%) and food gum (15%-20%). The flavoring agent, which is a requirement of these milks, is most preferably 70%-90% natural milk distillate plus natural vanilla.
Light-induced alterations in the chemistry of conventional milkfat-based dairy products have been recognized and studied for many years. These alterations which, it has been suggested, may involve protein (amino acid) and lipid reactions, lead to the formation of taste changes which are invariably undesirable. When most dairy products, including regular milkfat-based milks, are stored under artificial lighting, e.g., fluorescent lighting, such flavor alterations occur gradually over the life of the product. The level of off-flavor development depends upon many factors including the type of lighting, product proximity to the light source, length of exposure and fat level of the milk. For example, regular milk containing 1% by weight milkfat, when stored in a translucent plastic jug, may show slight to moderate oxidized flavor development after 12 hours of typical retail fluorescent lighting exposure (200 footcandle exposure, see Example 2 below). Light can also destroy a number of important vitamins in milk with varying speed. Several light-susceptible vitamins include vitamin A (retinol), its provitamin, beta-carotene, vitamin B2 (riboflavin) and vitamin C (ascorbic acid). The photosensitivity of vitamins A and B2 in milk has been examined. The level of vitamin A in milk decreases rapidly upon exposure to visible (violet) light below a wavelength of 415 nm and to a lesser degree at wavelengths between 415 nm and 455 nm, while vitamin B2 is degraded by light between the wavelengths of 415 nm and 455 nm (blue-violet). The rapidity of vitamin breakdown depends upon the intensity, duration and wavelength of light, the product storage temperature, and light transmittance through the product and its packaging. Skim milk, for example, is more transparent than regular milk (which contains emulsified fat), and its vitamins are therefore more susceptible to photodegradation.
Over the years, a variety of containers have been developed, which protect milks from the effects of natural and artificial light. These containers include printed paperboard cartons and pigmented and/or multi-layered plastic bottles. One such container is a white pigmented high density polyethylene (HDPE) jug recently brought to market by the H.P. Hood Company (Chelsea, Mass.). Tests of the one gallon and half gallon sizes of this so-called xe2x80x9cLight-Block Bottle(trademark)xe2x80x9d have shown that they block at least 85% to 90% of incident light between the wavelengths of 300nm and 700 nm. At 400nm and below, these containers block essentially all light.
Applicant has determined that in the consumption of dietary fat (as natural triglycerides) it is beneficial to maintain a specific ratio of saturated fatty acids to polyunsaturated fatty acids (at least 0.5:1 but less than 2:1) in the absence of cholesterol. Particularly, it is useful to ingest an adequate proportion of saturated fatty acids contributed by a vegetable oil source such as palm oil, palm olein or its equivalent combined with polyunsaturated fatty acids contributed by a vegetable oil source such as canola oil or soybean oil. Thus, the present invention relates to the dietary use of a cholesterol-free composition in which a balanced proportion of at least one saturated fatty acid such as palmitic acid, myristic acid, and lauric acid is provided together with an approximately equal proportion of at least one polyunsaturated fatty acid such as linoleic acid in the dietary fat. This balanced proportion can be achieved with a mixture of two or more vegetable oils and/or vegetable fats. Alternatively, with recent advances in plant breeding and selection using conventional or genetic engineering methods, the ratio of saturated to polyunsaturated fatty acids provided by single plant species can be manipulated. Thus, in the near future, with suitable plant breeding and selection, a vegetable oil-bearing single plant species may provide, within the range described above, a balanced proportion of saturated and polyunsaturated fatty acids. Furthermore, such plant breeding can provide an enhanced level of alpha-linolenic acid in addition to linoleic acid. There are already a number of examples of successful plant breeding or varietal selection efforts which have led to commercial alternatives in choosing a particular vegetable oil. For example, with the species Carthamus tinctotius (safflower), vareties of oil are available with either high oleic acid ( greater than 70%) or high linoleic acid ( greater than 70%). With the species Helianthus annuus (sunflower) varieties of oil are available with either medium ( less than 60%) or high ( less than 60%) levels of linoleic acid. Likewise, canola oil (rapeseed) is available from different varietal sources of two species (Brassica napus and B. campestris) with erucic acid (22:1) contents from zero to forty percent (see Baily""s Industrial Oil and Fat Products, Vol. 1, D. Swern, ed., Wiley and Sons, New York). Such a composition will increase HDL cholesterol and increase the HDL/LDL ratio (or decrease the LDL/HDL ratio) in the serum of mammals including humans and other primates. According to the present invention, a method is described for increasing the HDL/LDL ratio in human serum in which the HDL concentration increases while the LDL concentration remains essentially constant or decreases. Accordingly, when daily injested fat in the human diet is provided at a level such that it accounts for approximately 30% of the total dietary energy (as currently recommended by the nutritional research community), the saturated fatty acids including palmitic acid, or lauric and myristic acid must constitute between 20% and 40% by weight of the daily dietary fat, and the polyunsaturated fatty acids including linoleic acid must constitute between 15% and 40% by weight of this fat to maximize the serum HDL/LDL ratio. As one example, a cholesterol-free natural triglyceride fat blend containing equal proportions of approximately 30% by weight palmitic acid and 30% by weight linoleic acid plus linolenic acid is useful in the present invention. For this invention to be completely effective, it is important that certain cholesterolemic components be substantially absent from the diet. These components include but are not limited to dietary cholesterol and trans fatty acids, e.g., triglycerides containing elaidic acid produced during partial hydrogenation of vegetable oils. Illustrating this point with a human nutritional study, Sundram et al. (9 FASEB J. 000, 1995, Abstr.) have shown that exchanging trans 18:1 (elaidic acid) for cis 18:1 (oleic acid) caused a large increase in LDL and a decrease in HDL (where trans and cis 18:1 represented respectively, 7% and 16% of the dietary energy). This result and effect is opposite to the desired effect of the present invention.
Applicant has determined that a moderate proportion of saturated fatty acids is beneficial for increasing the HDL/LDL ratio in human serum and that a large proportion of polyunsaturated fatty acids in the dietary fat may, surprisingly, be undesirable in depressing this ratio.
Such advantages are achieved when the diet is essentially free of trans fats (e.g., elaidic) and represents the actual profile of fatty acid intake of the human.
Thus, in a first aspect, the invention features a method of increasing the HDL concentration and the HDL/LDL concentration ratio in human serum. This is achieved by providing a balance between a sufficient and required proportion of cholesterol-free saturated fatty acids in the daily dietary fat of a human, and a sufficient and required, but not excessive proportion of polyunsaturated fatty acids including linoleic acid in dietary fat. The remaining proportion of fatty acids and energy from dietary fat is provided by monounsaturated fatty acids including oleic acid. This means that the saturated fatty acids constitutes between 20% and 40% by weight of the daily dietary fat (based upon dietary fat accounting for 30% of the total dietary energy consumption). It also means that linoleic acid constitutes between 15% and 40% by weight of this dietary fat. These constituents will provide the required proportional intake of polyunsaturated fatty acids and thereby enhance the formation of HDL from VLDL and/or decrease the clearance of HDL. An excessive proportional intake of polyunsaturated fatty acids and monounsaturated fatty acids is also avoided in such a formulation to assure a sufficient dietary availability of saturated fatty acids which are required for sufficient VLDL synthesis and HDL production. Such a dietary fat composition is consistent with the dietary fat composition of the Step I diet of the American Heart Association.
In preferred embodiments, the cholesterol-free saturated fatty acids include palmitic acid, lauric acid and myristic acid; the proportion of monounsaturated fatty acids in the daily dietary fat is between 20% and 50% oleic acid and no greater than 1% elaidic acid (or other unnatural trans fatty acids) by weight; the polyunsaturated fatty acids include linoleic acid and at least one other polyunsaturated fatty acid selected from the group including alpha-linolenic acid, eicosapentenoic acid (EPA), and docosahexenoic acid (DHA); and the proportion of saturated fatty acids in the daily dietary fat is at least 20% by weight and dietary fat has less than 5% by weight stearic acid.
In a second related aspect, the invention features a method of stabilizing or decreasing the LDL concentration in human serum by providing saturated fatty acids in the daily diet in a proportion between 20% and 40% by weight of the daily dietary fat (based upon dietary fat accounting for 30% of the total dietary energy consumption), and maintaining a proportion of polyunsaturated fatty acids (including linoleic acid) in the daily diet at the expense of monounsaturated fatty acids (including oleic acid and/or elaidic acid). The linoleic acid constitutes between 15% and 40% by weight of dietary fat. Removal of plasma VLDL remnants and LDL is maximized by this formulation, and the production of LDL is reduced.
In a third related aspect, the invention features a method of increasing the HDL and stabilizing or decreasing the LDL concentration in human serum by providing saturated fatty acids in the daily diet in a proportion between 20% and 40% by weight of the daily dietary fat (based upon dietary fat accounting for 30% of the total dietary energy consumption), whereby the production of VLDL, as the HDL precursor, is adequately sustained and is not limiting in HDL biosynthesis. In addition, the method includes maintaining a proportion of polyunsaturated fatty acids (including linoleic acid) in the daily diet at the expense of monounsaturated fatty acids (including oleic acid and/or elaidic acid), wherein linoleic acid constitutes between 15% and 40% by weight of dietary fat, whereby VLDL catabolism to HDL is facilitated and hepatic clearance of VLDL remnants and LDL is enhanced.
In a fourth related aspect, the invention features a method of increasing the HDL concentration and the HDL/LDL concentration ratio in human serum by the dietary consumption of foods prepared using a cholesterol-free single fat composition or blended fat composition containing a ratio of one part by weight polyunsaturated fatty acids to at least one part by weight saturated fatty acids. The single fat composition or blended fat composition includes linoleic acid and at least one saturated fatty acid selected from the group including lauric acid, myristic acid, and palmitic acid. The linoleic acid constitutes between 15% by weight and 40% by weight of the composition and saturated fatty acid constitutes between 20% and 40% by weight of the composition. In this way, adequate dietary levels of saturated fatty acids in the absence of cholesterol stimulate VLDL synthesis and secretion by the liver, and adequate dietary levels of linoleic acid enhance LPL activity and generation of HDL from VLDL while stimulating the removal of VLDL remnants and LDL, and concommitently decreasing CETP activity and HDL catabolism.
In preferred embodiments of the above aspects, the food source of saturated fatty acids includes at least one vegetable fat selected from the group including palm fat, coconut fat and cocoa butter; the palm fat is selected from the group including palm oil, palm olein, and palm kernel oil; the food source of polyunsaturated fatty acids includes at least one vegetable oil selected from the group including corn oil, sunflower oil, safflower oil, soybean oil, cottonseed oil, canola oil, and peanut oil; alternatively, the food source of both saturated fatty acids and polyunsaturated fatty acids is a single vegetable oil species which has been selected or engineered to provide the requisite balance of saturated and polyunsaturated fatty acids; the polyunsaturated fatty acids include linoleic acid and linolenic acid; wherein linolenic acid is contributed by soybean oil, canola oil, edible flax seed oil, and/or perrilla seed oil; within the single fat composition or blended fat composition is provided a proportion of at least one part by weight cholesterol-free saturated fat to one part by weight polyunsaturated fat to stabilize the polyunsaturated fat against oxidation; the oxidation-resistance of the single fat or blended fat composition upon heating to a temperature of 100.degree. C. or greater in air is increased by at least 25% compared to the oxidation resistance of the polyunsaturated fat component when heated separately from the single fat or blended fat composition; essentially all of dietary fat is provided in a nutritionally balanced liquid and/or solid formula diet in which dietary fat accounts for between 15% and 45% of the total dietary energy consumption; the dietary fat accounts for between 20% and 30% of the total dietary energy consumption; the compositions noted above are used in place of dietary consumption of foods prepared using a blended fat composition, that is, such foods are substituted with the dietary consumption of a nutritionally balanced liquid formula diet prepared using a single fat or blended fat composition in which the total fat content therein accounts for between 15% and 45% of the total dietary energy consumption; daily dietary fat or foods contain a blended fat composition including one part by weight of at least one polyunsaturated vegetable oil selected from the group including corn oil, sunflower oil, safflower oil, soybean oil, cottonseed oil, canola oil, and peanut oil blended with at least one part by weight of vegetable fat including saturated fatty acids; the vegetable fat is selected from the group including palm fat, coconut fat and cocoa butter; and the palm fat is selected from the group including palm oil, palm olein, and palm kernel oil. Alternatively the daily dietary fat or foods contain a single vegetable oil species which has been selected or engineered to provide the requisite balance of saturated and polyunsaturated fatty acids.
In a fourth related aspect, the invention features a method of increasing the HDL concentration and the HDL/LDL concentration ratio in human serum by the dietary consumption of foods. These foods are prepared using at least one modified fat selected from the group including a chemically interesterified fat, an enzymatically interesterified fat, and a synthetic fat. The modified fat includes one part by weight polyunsaturated fatty acids and at least one part by weight saturated fatty acids selected from the group including lauric acid, myristic acid, and palmitic acid. The polyunsaturated fatty acids constitute between 15% by weight and 40% by weight of modified fat, and the saturated fatty acids constitute between 20% and 40% by weight of modified fat. In this way adequate dietary levels of saturated fatty acids in the absence of cholesterol stimulate VLDL synthesis and secretion by the liver, and adequate dietary levels of polyunsaturated fatty acids enhance LPL activity and generation of HDL from VLDL while stimulating the removal of VLDL remnants and LDL and concommitently decreasing CETP activity and HDL catabolism (FIG. 1).
Preferably, the weight ratio of saturated fatty acids to polyunsaturated fatty acids included in dietary fat, modified fat, or blended fat composition ranges from 0.5:1.0 to 2.0:1.0; and the weight ratio is approximately (xc2x120%) 1 to 1.
In a fifth related aspect, the invention features a liquid and/or solid dietary composition suitable for human or animal ingestion for increasing the HDL concentration and the HDL/LDL concentration ratio in the blood serum. Essentially all of dietary fat which accounts for between 15% and 45% of the total dietary energy in liquid formula diet, is provided by a single fat or a blended fat composition containing one part by weight polyunsaturated fat and at least one part by weight cholesterol-free saturated fat. The single fat or blended fat composition includes linoleic acid and at least one saturated fatty acid selected from the group including lauric acid, myristic acid, and palmitic acid. The linoleic acid constitutes between 15% by weight and 40% by weight of the composition, and saturated fatty acid constitutes between 20% and 40% by weight of composition.
In preferred embodiments, dietary fat accounts for between 20% and 30% of the total dietary energy in the liquid formula diet; the saturated fatty acid is predominantly palmitic acid; and a reduction in cardiac arrythmia accompanies the increase in HDL concentration and the increase in HDL/LDL concentration ratio.
Suitable sources for cholesterol-free fats containing saturated fatty acids include saturated vegetable fats such as palm fat, coconut fat, and cocoa butter. Palm oil, palm olein, and palm kernel oil are particularly useful sources for the saturated fatty acids. Suitable sources for polyunsaturated fatty acids include the vegetable oils which are rich in linoleic acid such as corn oil, sunflower oil, safflower oil, soybean oil, and cottonseed oil for example. The above-mentioned vegetable fats and oils can be blended in appropriate ratios according to the content of the above-mentioned saturated and polyunsaturated fatty acids therein, to produce dietary fat blends having the recommended proportions by weight of saturated and polyunsaturated fatty acids (see Tables I and II for the fatty acid content of various vegetable fats and oils as derived from published data greater than Agriculture Handbook No. 8-4, U.S.D.A. Science and Education Administration, Composition of Foods: Fats and Oils!).
For example, two parts palm oil (44% palmitic acid, 9% linoleic acid) can be blended with one part corn oil (11% palmitic acid, 58% linoleic acid) to provide a balanced fat blend containing approximately 33% palmitic acid (16:0) and 25% linoleic acid (18:2). Such cholesterol-free balanced fat blends are useful not only as dietary constituents that modulate plasma cholesterol to maximize the HDL/LDL ratio but also provide advantageous use in various cooking procedures such as in deep-fat frying. The fat blends may also be used in shortening for baked prepared foods (including cakes, pies, cookies, crackers, etc.), in dairy products (including frozen desserts, creams, cheeses, spreads), and in blended food products (including salad dressing, margarines, mayonnaise). In addition the fat blends may be used in liquid and/or solid dietary compositions for managing and controlling food intake such as for weight loss, control of hypercholesterolemia, or for managing any one of a variety of health conditions requiring a controlled diet in which the proportion and composition of the dietary fat must be controlled. As a practical matter, the balanced mixture of saturated and polyunsaturated fatty acids can be provided not only as a natural blend of cholesterol-free saturated fats and polyunsaturated oils, but also as a mixed fatty acid composition in the form of one or more modified or synthetic fats incorporating chemically or enzymatically interesterified fatty acids to achieve the balanced proportion of saturated and polyunsaturated fatty acids described in this invention.
The present invention also relates to a filled dairy product, such as milk, containing an emulsified polyunsaturated vegetable oil together with milkfat, where the fats are present in specified percentage ranges, and in which the product is substantially free of any flavoring agent. Compared to simple milkfat-based dairy products, the fat component of the filled dairy product contains a substantially increased proportion of polyunsaturated fatty acids and a substantially decreased proportion of saturated fatty acids and cholesterol. The invention also involves reducing or eliminating off-flavors which develop when polyunsaturated vegetable oils are emulsified into these dairy products, by excluding more than 90% of ambient visible light from the dairy products.
It has been shown that a pre-mix containing milkfat (or a cream rich in milkfat), plus a polyunsaturated vegetable oil (such as soybean oil) plus an effective amount of emulsifier (such as mono- and diglycerides), can be dispersed into skim milk (or reduced fat milk, or regular milk), and then pasteurized, homogenized and appropriately packaged in an opaque container. Suitable light-opaque packaging is used to achieve an adequate shelf-life and to sustain fresh taste in these filled dairy products. This discovery was surprising because Applicants expected that addition of the fat-soluble antioxidant, vitamin E, to the milk would protect the milk with its polyunsaturated fatty acids against air oxidation and off-flavor development. From the prior art, it was also anticipated that the addition of a suitable antioxidant (such as BHA, BHT, TBHQ or tocopherol) would protect the filled dairy products. Instead, it was found that vitamin E addition was of little help, while light exclusion was of great help. Simply stated, photochemical change in a polyunsaturated fat-filled dairy product appears to be the predominant source of off-flavors, and the xe2x80x9cfirst line of defensexe2x80x9d for these products must be light-excluding packaging (see Examples below).
The problem of development of off-flavors in filled milk products has been recognized (e.g., Strong et al., U.S. Pat. No. 5,580,600) and has resulted in the absence of such products in the market, and apparently discouraged development in this area. While the existence of the problem was acknowledged, neither the source of the problem, nor a solution directed to that source were shown. Instead, filled milk products utilized replacement fats which were more resistant to the development of off-flavors than polyunsaturated fats (e.g., monounsaturated vegetable oils or partially hydrogenated vegetable oils) or utilized flavor additives which would mask the development of off-flavors (e.g., milk distillate plus vanilla).
In contrast, for the present invention, photochemical changes in filled dairy products containing polyunsaturated vegetable oils were found to be at least a major, and apparently a predominant, factor in the development of off-flavors. It was further found that flavor stability could be maintained by preventing substantial exposure of the filled dairy product to light, particularly to visible wavelengths of light. By limiting or preventing exposure to visible light, it became practical to produce filled milk products which included a high proportion of polyunsaturated fats without the need to include a flavoring agent to mask the development of off-flavors.
It was also found that a filled milk product (or other filled dairy product) containing a substantial proportion of polyunsaturated vegetable oil could be produced, in which the balance between saturated fats and polyunsaturated fats is consistent with the ranges recommended in Sundram et al., U.S. Pat. No. 5,578,334 and Sundram et al, U.S. Pat. No. 5,843,497, which are hereby incorporated by reference in their entireties, including drawings. Those ranges were shown to sustain or enhance the HDL/LDL ratio in humans who ingested a diet with such a fat balance, preferably when cholesterolemic components such as elaidic acid were limited. It was further found that such a dairy product provided good taste and mouthfeel (much like regular milk) and that the taste could be preserved by limiting light exposure. As a result, it is practical to provide such milk or dairy products for general distribution.
Thus, the invention features a polyunsaturated vegetable oil-filled dairy product substantially free of any flavoring agent, in which the fat portion of the dairy product includes at least one polyunsaturated vegetable oil and milkfat. The fat portion includes between 15% and 40% by weight linoleic acid, between approximately 20% and 40% by weight saturated fatty acids, and no more than 1% by weight elaidic acid or other unnatural trans fatty acids. The fat portion and the aqueous portion of the dairy product constitute a stable emulsion. Generally the stable emulsion is provided by utilizing an effective concentration of at least one emulsifier capable of maintaining the vegetable oil and the milkfat as a stable emulsion in the dairy product. Flavor stability is provided by excluding or limiting exposure of the filled dairy product to visible light.
In preferred embodiments, the weight ratio of vegetable oil to milkfat in the fat portion of the filled dairy product is between approximately 2:1 and 1:2, preferably between 1.5:1 and 1:1.5. In preferred embodiments, the fat portion of the filled dairy product contains between approximately 20% and 40% by weight saturated fatty acids selected from the group consisting of palmitic acid, myristic acid, lauric acid, stearic acid, and combinations thereof.
In preferred embodiments, the dairy product is contained within a substantially light-opaque container which is used to exclude between 90% and 100% of visible light between the wavelengths of 300 nm and 700 nm which is incident upon the container, and the dairy product thereby can retain acceptable flavor after the container has received at least 24 hours cumulative exposure to at least 200 footcandles illumination at a temperature of 38xc2x0 F. Illumination is typically in the form of artificial lighting, e.g., fluorescent lighting tubes, using warm white, cool white or some combination of these well known fluorescent lighting sources. The dairy product is placed in a substantially light-opaque container, in which the walls of the container are preferably fabricated from a material selected from the group consisting of opaque paperboard, pigmented thermoplastic resin and combinations thereof.
xe2x80x9cAcceptable flavorxe2x80x9d means that the filled dairy product does not have a level of development of off-flavors as to render the product unsuitable for general consumption by humans. This can be demonstrated by taste-testing using a panel of individuals, or preferably using at least two expert taste testers as in Example 2 below, where the average score on the described 1 to 5 scale is at least 4, preferably at least 4.5.
The term xe2x80x9csubstantially light opaquexe2x80x9d means that at least 90% of the incident light is blocked, preferably at least 95%, more preferably at least 98%, and most preferably at least 99%.
In preferred embodiments, the fat portion of the filled dairy product further includes between 0.2% by weight and 10% by weight of the polyunsaturated fatty acid, linolenic acid; the cholesterol content of the filled dairy product is preferably reduced by at least 25% compared to a dairy product containing the same percentage by weight of fat which is limited solely to regular milkfat, i.e., unmodified milkfat; the filled dairy product is a filled milk which contains between 0.2% by weight and 20% by weight of at least one milkfat selected from the group consisting of regular milkfat and cholesterol-reduced milkfat; the cholesterol-reduced milkfat contains less than 10% of its original cholesterol content; the polyunsaturated vegetable oil is selected from the group consisting of soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil, peanut oil and combinations thereof; the emulsifier includes a mixture of mono- and di-glycerides. The mono- and di-glycerides are preferably selected from the group consisting of glyceryl mono- and di-stearates, glyceryl mono- and di-oleates and combinations thereof.
In preferred embodiments, the filled dairy product is a filled milk product which, upon analysis or fractionation, includes between 55% and 99% by weight skim milk, between approximately 0.4% and 20% by weight of polyunsaturated vegetable oil, between approximately 0.4% by weight and 20% by weight of milkfat, and between approximately 0.1% and 5% of emulsifier; the filled dairy product is selected from the group consisting of filled milk, filled butter milk, filled cream, filled yogurt, filled sour cream, filled egg nog, filled ice cream, filled cottage cheese and filled cheese; the content of fat in the filled dairy product is selected from the group consisting of full fat content, reduced fat content and low fat content.
In a related aspect, the invention features a polyunsaturated vegetable oil-filled milk substantially free of any flavoring agent, as described for the filled dairy product of the aspect above. As in the above aspect, flavor stability is provided by excluding or limiting exposure to visible light. The filled milk includes a combination of skim milk and a substitute fat, in which the substitute fat contains at least 20% less saturated fat and cholesterol than would the same amount of regular milkfat. The substitute fat includes a combination of at least one polyunsaturated vegetable oil and milkfat, in which the substitute fat contains between 15% and 40% by weight linoleic acid, between approximately 20% and 40% by weight saturated fatty acids, and no more than 1% by weight elaidic acid or other unnatural trans fatty acids. The substitute fat and the aqueous portion are prepared as a stable emulsion. As in the aspect above, generally preparation of the stable emulsion involves inclusion of an effective amount of emulsifier capable of maintaining the combination of vegetable oil and milkfat as a stable emulsion.
In preferred embodiments, the polyunsaturated vegetable oil in the filled dairy product is selected from the group consisting of soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil, peanut oil and combinations thereof. Preferred embodiments are also as described for the aspect above. In addition, as described in Sundram et al., U.S. Pat. No. 5,843,497, in this aspect and other aspects of this invention, a vegetable oil may be or include a genetically-engineered vegetable oil, and/or a modified or synthetic fat incorporating enzymatically or chemically interesterified fatty acids.
In another related aspect, the invention provides a filled dairy product substantially free of any flavoring agent. Again, flavor stability is provided by excluding or limiting exposure to visible light. The filled dairy product contains a substitute fat which includes milkfat and at least one polyunsaturated vegetable oil in a weight ratio ranging from approximately 1:2 to approximately 2:1. The substitute fat portion of the filled dairy product contains between 15% and 40% by weight linoleic acid, between approximately 15% and 40% by weight saturated fatty acids, and no more than 1% by weight elaidic acid or other unnatural trans fatty acids. The substitute fat and the aqueous portion form a stable emulsion. As indicated above, generally provision of the stable emulsion involves inclusion of an effective concentration of at least one emulsifier capable of maintaining the substitute fat as a stable emulsion in the dairy product.
In preferred embodiments, the polyunsaturated vegetable oil in the filled dairy product is selected from the group consisting of soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil, peanut oil and combinations thereof. Preferred embodiments are also as described for the first aspect above.
In another aspect, the invention features a method of reducing or preventing development of off-flavors in a polyunsaturated vegetable oil-containing filled dairy product, and thereby obviating the need for including any flavoring agent. The method includes packaging the filled dairy product in a substantially light-opaque container excluding between 90% and 100% of visible light between the wavelengths of 300 nm and 700 nm which is incident upon the container, and limiting the intensity of the visible light entering the filled dairy product to between zero and 40 footcandles during multi-hour storage of the filled dairy product. The filled dairy product includes at least one polyunsaturated vegetable oil and milkfat, and is provided as a stable emulsion, e.g., by utilizing an effective concentration of at least one emulsifier capable of maintaining the vegetable oil and the milkfat as a stable emulsion in the filled dairy product.
In preferred embodiments of the method, the fat portion of the filled dairy product, which includes polyunsaturated vegetable oil and milkfat, contains between 15% and 40% by weight linoleic acid, between approximately 20% and 40% by weight saturated fatty acids, and no more than 1% by weight elaidic acid or other unnatural trans fatty acids.
Additional preferred embodiments include components as described for the first aspect above. Thus, in preferred embodiments of the method, the weight ratio of vegetable oil to milkfat in the fat portion of the filled dairy product is between approximately 2:1 and 1:2, preferably between 1.5:1 and 1:1.5.
In preferred embodiments of the method, the fat portion of the filled dairy product which includes milkfat, contains between approximately 20% and 40% by weight saturated fatty acids selected from the group consisting of palmitic acid, myristic acid, lauric acid, stearic acid, and combinations thereof.
In preferred embodiments of the method, the dairy product retains acceptable flavor after the exterior surface of the container has been cumulatively exposed to at least 200 footcandles illumination at a temperature of 38xc2x0 F. for up to 14 days. The walls of the container are preferably fabricated from a material selected from the group consisting of opaque paperboard, pigmented thermoplastic resin and combinations thereof.
In other preferred embodiments of the method, the fat portion of the filled dairy product further includes between 0.2% by weight and 10% by weight linolenic acid. Among the vegetable oils, soybean oil is relatively rich in linolenic acid, the triply unsaturated eighteen carbon essential fatty acid (18:3). Also in preferred embodiments, the cholesterol content is reduced by at least 25% compared to a dairy product containing the same percentage by weight of fat which is limited solely to regular milkfat; the dairy product is a filled milk which includes between 0.2% by weight and 20% by weight of at least one milkfat selected from the group consisting of regular milkfat and cholesterol-reduced milkfat; the cholesterol-reduced milkfat contains less than 10% of its original cholesterol content; the polyunsaturated vegetable oil is selected from the group consisting of soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil, peanut oil and combinations thereof; the emulsifier includes a mixture of mono- and di-glycerides, and preferably the mono- and di-glycerides are selected from the group consisting of glyceryl mono- and di-stearates, glyceryl mono- and di-oleates and combinations thereof; the dairy product is a filled milk product which, upon analysis or fractionation, comprises between 55% and 99% by weight skim milk, between approximately 0.4% and 20% by weight of polyunsaturated vegetable oil, between approximately 0.4% by weight and 20% by weight of milkfat, and between approximately 0.1% and 5% of emulsifier; the dairy product is selected from the group consisting of filled milk, filled butter milk, filled cream, filled yogurt, filled sour cream, filled egg nog, filled ice cream, filled cottage cheese and filled cheese; the content of fat in the dairy product is selected from the group consisting of full fat content, reduced fat content and low fat content dairy products.
In still another aspect, the invention features a method of substantially reducing the rate of development of off-flavors in a polyunsaturated vegetable oil-filled milk, and thereby obviating the need for including any flavoring agent therein. The filled milk is packaged in a substantially light-opaque container, preferably excluding at least 90% of visible light between the wavelengths of 300 nm and 700 nm which is incident upon the container. The intensity of the visible light entering the filled milk is limited to less than 40 footcandles during multi-hour storage of the filled milk. The fat portion of the filled milk contains between 15% and 40% by weight linoleic acid, between approximately 20% and 40% by weight saturated fatty acids, no more than 1% by weight elaidic acid or other unnatural trans fatty acids, and at least 25% less cholesterol than regular milkfat on a weight percentage basis. The filled milk is prepared as a stable emulsion, e.g., by including an effective concentration of at least one emulsifier capable of maintaining the vegetable oil and the milkfat as a stable emulsion in the filled milk.
In preferred embodiments of this method, the fat portion of the filled milk includes milkfat and at least one polyunsaturated vegetable oil in a weight ratio ranging from approximately 1:2 to approximately 2:1; the polyunsaturated vegetable oil is selected from the group consisting of soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil, peanut oil and combinations thereof.
For the purposes of this invention, the following terms have the following definitions or meanings in context. The term xe2x80x9cfilled dairy productxe2x80x9d refers to a milk-containing product which contains milk which is enriched in fat content by the addition of vegetable oils. Generally, a skim milk will be used, to which will be added a fat-containing component.
The term xe2x80x9csubstantially freexe2x80x9d, in the context of describing the presence of flavoring agent, differentiates the present compositions from compositions in which an added flavoring component or components is needed to mask off-flavors in the base dairy product, e.g., in a filled milk such as in Kahn et al., U.S. Pat. No. 5,063,074, in which a flavoring agent must be added. Thus, xe2x80x9csubstantially freexe2x80x9d means that no flavoring agent is added into the basic filled dairy product to provide a flavor-stable product having the taste and mouthfeel of a dairy product having the same total fat content as milkfat only (rather than polyunsaturated vegetable oil plus milkfat). However, this term is not meant to prevent a manufacturer from adding ingredients to produce derivative dairy products such as fruit yogurts, which differ in flavor from the original or basic dairy products.
The term xe2x80x9cflavor stabilityxe2x80x9d is defined as maintaining a constant and high quality flavor (a score of at least 4 points, preferably at least 4.5 points, more preferably 5 points) over at least 14 days refrigeration at 38xc2x0 F., as monitored and scored by at least two (or 3,4,5, or more) professional dairy product tasters (see Example 2).
The term xe2x80x9creduced proportionxe2x80x9d in the context of saturated fat and cholesterol content means that there is at least a 20% reduction, and preferably a 25% reduction in the concentration (percentage by weight) of these materials in the product. More preferably the reduction is 50%, 75%, 90%, or more.
The term xe2x80x9cpolyunsaturated vegetable oilxe2x80x9d refers to natural vegetable oils which are typically refined and deodorized, and preferably retain their natural triglyceride structure, rather than being either chemically modified, e.g., by interesterification, or by hydrogenation to reduce their content of esterified linoleic and linolenic fatty acids (polyunsaturated fatty acids). If modified, the polyunsaturated vegetable oil preferably contains less than 1% by weight elaidic acid or other unnatural trans fatty acids. A non-exclusive list of the common polyunsaturated vegetable oils includes soybean oil, corn oil, cottonseed oil, canola oil, sunflower oil, safflower oil and peanut oil. The polyunsaturated vegetable oils contain more than 25% by weight of linoleic acid plus linolenic acid. By contrast, certain vegetable oils including palm oil and coconut oil are considered saturated fats, containing at least 35% by weight saturated fatty acids such as palmitic and stearic acids, and less than 20% by weight polyunsaturated fatty acids. Anhydrous milkfat is a highly saturated fat, containing more than 60% saturated fatty acids, less than 30% monounsaturated fatty acid (oleic acid), and less than 5% polyunsaturated fatty acid (linoleic acid). Regular milkfat, i.e., butter contains approximately 16% water. Consequently, its fatty acid content is slightly lower, i.e., approximately 51% by weight saturated fatty acids, 23% monounsaturated fatty acids, and 3% polyunsaturated fatty acids.
The term xe2x80x9cstable emulsionxe2x80x9d in the context of the present invention means that the fat component of the filled dairy product (such as filled milk) does not physically separate to form a second liquid phase during the lifetime, i.e., shelflife, of the product. Thus, the absence of such a second liquid phase preferably persists for at least 1 week, more preferably at least 1xc2xd weeks or 2 weeks, still more preferably at least 2xc2xd or 3 weeks, and most preferably 4 weeks or longer. Usually, the formation and/or maintenance of the stable emulsion involves the incorporation of an adequate concentration (also termed an xe2x80x9ceffective concentrationxe2x80x9d) of a food additive which aids in preventing separation of fats from the aqueous phase, e.g., an FDA approved, food grade emulsifier such as the mono- and diglycerides of stearic acid, oleic acid, and combinations thereof. In milk-type products, the stable emulsion is an oil-in-water type emulsion, meaning that microscopic droplets of milkfat and/or oil are dispersed as the internal phase, and the aqueous milk is the external phase.
The term xe2x80x9cfat portionxe2x80x9d in connection with a dairy product refers collectively to all fats and oils in the product, including, for example, milkfat and/or vegetable oils, along with any additional components solubilized or suspended in an oil phase. Such an oil phase may, for example, be an oil droplet or droplets of an oil-in-water emulsion. Similarly, the term xe2x80x9caqueous portionxe2x80x9d refers to the water (i.e., aqueous) component along with non-fat and non-oil components solubilized or suspended in the water. Thus, for example, such components can include water-soluble proteins and mineral ions.
The term xe2x80x9clight-opaquexe2x80x9d in the context of a container which is suitable for protecting the filled dairy products, excludes at least 90% of visible light (between the wavelengths of 300 nm and 700 nm) which is incident upon the container, and preferably 95%, 98%, 99%, or more. The term xe2x80x9cphotodegradationxe2x80x9d is used to describe chemical damage to the filled dairy product resulting from the action of light upon the product. As a process, it includes but is not limited to photooxidation. Photooxidation as a process requiring both oxygen and light energy input, is distinct from simple oxidation, which can occur in the dark. Opaque packaging material, rather than oxygen-excluding packaging, is used in the present invention because the former is inexpensive and has been shown to be effective in preventing development of off-flavors in the polyunsaturated fatty acid-filled products of the present invention. Moreover, opaque packaging will prevent all forms of photodegradation (including photooxidation), and such packaging is less expensive and more practical than packaging to exclude oxygen over the lifetime of the dairy product.
The term xe2x80x9cartificial bright light storagexe2x80x9d refers to typical lighting conditions used in the commercial retailing of dairy products. While incandescent illumination is included in this term, most retail stores such as supermarkets employ fluorescent lighting inside or outside of refrigerated storage units. In this context, the artificial light intensity in dairy display units may, for example, range from 20 and 500 footcandles. However, to provide reliable protection in xe2x80x9cbright lightxe2x80x9d display units, preferred packaging materials should allow the filled dairy product to retain acceptable flavor after exposure to 200 footcandles illumination at a temperature of 38xc2x0 F. for 14 days. With regard to light-excluding, i.e., xe2x80x9copaquexe2x80x9d, containers, these include, for example, both paperboard cartons and plastic or glass bottles. The walls of the containers exclude at least 90% (Optical Density of at least 1.0, and preferably 98% (Optical Density of at least 1.7) of the incident visible light as described above. Opaque paperboard cartons which are generally coated with a thin layer of polyethylene, and which hold either one or two quarts liquid were obtained from the International Paper Company. Opaque white polyethylene bottles capable of holding from one pint to one gallon were obtained from Shelburne Plastics, Inc.
The term xe2x80x9coff-flavorsxe2x80x9d in the context of a dairy product refers to any new taste or smell, often volatile and unpleasant which may appear following initial packaging. Some common off-flavors include rancid or oxidized fat flavor, acid or sour flavor, musty or earthy flavor, sulfurous flavor, acetone-like flavor and tallowy flavor.
A xe2x80x9cflavoring agentxe2x80x9d, defined in the same context, is an edible substance which, when added to a dairy product, beneficially alters the taste or smell of the product (see Kahn et al., U.S. Pat. No. 5,063,074 for a detailed definition). The flavoring agent may be used to correct or mask an off-flavor, e.g., chocolate or banana flavor. Alternatively, the flavoring agent may replace or reinforce a natural dairy flavor such as a mikfat-associated flavor which is lacking in skim milk-derived products. Thus, in a filled dairy product which lacks milkfat but contains a non-tropical vegetable oil (e.g., Kahn et al., U.S. Pat. No. 5,063,074), a premix is added, which combines natural milk distillate as a flavoring agent. In fact, it is the experience of Applicants that a tasteless and odorless vegetable oil, such as that described by Kahn et al., contributes an unpleasant oily mouthfeel and aftertaste to a filled dairy product, which otherwise lacks milkfat. Such a deficiency in flavor and mouthfeel is evident in a filled milk containing soybean oil and lacking milkfat (and furthermore, lacking any flavoring agent; see Example 6 below, Group A results). This deficiency only becomes more significant with aging of the filled dairy product as oxidized flavors become more obvious.
Filled dairy products described in the present invention may contain unmodified milkfat, i.e., regular milkfat, or alternatively, milkfat which has been separately treated to remove or extract cholesterol, e.g., by a non-hydrogenation procedure such as described by Marschner et al. in U.S. Pat. Nos. 4,804,555 and 4,996,072 and other equivalent methods known in the art, for example, employing supercritical fluid extraction, or extraction using cyclodextrans. Such treated milkfats are termed herein cholesterol-reduced.
With regard to the relative fat content of a particular type of dairy product, the term xe2x80x9cfull fatxe2x80x9d refers to the standard food identity fat content, e.g., milk, approximately 3.25% fat by weight, and butter, approximately 80% fat by weight. The term xe2x80x9creduced fatxe2x80x9d content refers to a decrease of at least 25% below the regular or xe2x80x9cfull fatxe2x80x9d content of the food product. The term xe2x80x9clow fatxe2x80x9d content refers to a food product containing no more than 3 g of fat per serving. For milk having a serving size of 244 g, the 3 g fat limit defines low fat milk as containing no more than 1.23% by weight fat.
By xe2x80x9ccomprisingxe2x80x9d is meant including, but not limited to, whatever follows the word xe2x80x9ccomprisingxe2x80x9d. Thus, use of the term xe2x80x9ccomprisingxe2x80x9d indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present. By xe2x80x9cconsisting ofxe2x80x9d is meant including, and limited to, whatever follows the phrase xe2x80x9cconsisting ofxe2x80x9d. Thus, the phrase xe2x80x9cconsisting ofxe2x80x9d indicates that the listed elements are required or mandatory, and that no other elements may be present. By xe2x80x9cconsisting essentially ofxe2x80x9d is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase xe2x80x9cconsisting essentially ofxe2x80x9d indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they affect the activity or action of the listed elements.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.